The field of invention relates generally to nano-fabrication of structures. More particularly, the present invention is directed to a method for improving contact imprinting employed in imprint lithographic processes.
Nano-scale fabrication involves the fabrication of very small structures, e.g., having features on the order of one nanometer or more. A promising process for use in nano-scale fabrication is known as imprint lithography. Exemplary imprint lithography processes are described in detail in numerous publications, such as United States published patent application 2004/0065976 filed as U.S. patent application Ser. No. 10/264,960, entitled “Method and a Mold to Arrange Features on a Substrate to Replicate Features having Minimal Dimensional Variability”; United States published patent application 2004-0065252 filed as U.S. patent application Ser. No. 10/264,926, entitled “Method of Forming a Layer on a Substrate to Facilitate Fabrication of Metrology Standards”; and U.S. Pat. No. 6,936,194, entitled “Method and a Mold to Arrange Features on a Substrate to Replicate Features having Minimal Dimensions Variability”; all of which are assigned to the assignee of the present invention.
Referring to FIG. 1, the basic concept behind imprint lithography is forming a relief pattern on a substrate that may function as, inter alia, an etching mask so that a pattern may be formed into the substrate that corresponds to the relief pattern. A system 10 employed to form the relief pattern includes a stage 11 upon which a substrate 12 is supported, and a template 14 having a mold 16 with a patterning surface 18 thereon. Patterning surface 18 may be substantially smooth and/or planar, or may be patterned so that one or more recesses are formed therein. Template 14 is coupled to an imprint head 20 to facilitate movement of template 14. A fluid dispense system 22 is coupled to be selectively placed in fluid communication with substrate 12 so as to deposit polymerizable material 24 thereon. A source 26 of energy 28 is coupled to direct energy 28 along a path 30. Imprint head 20 and stage 11 are configured to arrange mold 16 and substrate 12, respectively, to be in superimposition, and disposed in path 30. Either imprint head 20, stage 11, or both vary a distance between mold 16 and substrate 12 to define a desired volume therebetween that is filled by polymerizable material 24. The relative positions of substrate 12 and stage 11 is maintained employing standard chucking techniques. For example, stage 11 may include a vacuum chuck, such as a pin chuck (not shown) coupled to a vacuum supply (not shown).
Typically, polymerizable material 24 is disposed upon substrate 12 before the desired volume is defined between mold 16 and substrate 12. However, polymerizable material 24 may fill the volume after the desired volume has been obtained. After the desired volume is filled with polymerizable material 24, source 26 produces energy 28, which causes polymerizable material 24 to solidify and/or cross-link, forming polymeric material conforming to the shape of the substrate surface 25 and mold surface 18. Control of this process is regulated by processor 32 that is in data communication with stage 11 imprint head 20, fluid dispense system 22, and source 26, operating on a computer-readable program stored in memory 34.
An important characteristic with accurately forming the pattern in polymerizable material 24 is to ensure that the dimensions of the features formed in the polymerizable material 24 are controlled. Otherwise, distortions in the features etched into the underlying substrate may result.
A need exists, therefore, to improve the imprinting technique employed in contact lithographic processes.